1. Field of the Invention
The present invention relates to an oscillation apparatus for adjusting the oscillation state of an oscillating roller of an ink supply apparatus of a printing press.
2. Description of the Related Art
When securities or the like are printed, rainbow printing is performed for prevention of forgery. When such rainbow printing is performed, an oscillation apparatus for adjusting the oscillation state of an oscillating roller of an ink supply apparatus plays an very important role. Such a conventional oscillation apparatus will be described with reference to FIG. 12.
Ink stored in an ink fountain of an ink supply apparatus is supplied to oscillating rollers 101 and 102 of a printing press; and a hydraulic pump 112 is operated in order to feed a working fluid from a hydraulic tank 111 to a hydraulic cylinder 115. As a result, the oscillating roller 101 is reciprocated along its axial direction, and the oscillating roller 102 is also reciprocated along its axial direction via an oscillation lever 103, so that ink is supplied to a plate cylinder while being spread in the axial direction of the oscillating rollers 101 and 102.
The oscillation number of the oscillating roller 102 is converted to an electrical signal by means of a differential transformer 118, and the electrical signal is fed to an amplifier 116. The number of revolutions of an impression cylinder 100 is converted to a pulse signal by means of a rotary encoder 117, and the pulse signal is fed to the amplifier 116. When the oscillation width of the oscillating rollers 101 and 102 is set through operation of a volume 119, the signals fed to the amplifier 116 and the set oscillation width are computed in order to obtain a signal indicating a set value, which is output to a flow control valve 113. Further, while the value set by use of the volume 119 and the signal from the differential transformer 118 are compared with each other, pulses from the rotary encoder 117 are computed in order to output a signal to a direction control valve 114 at a predetermined timing that matches operation of the printing press. Through the above-described operation performed continuously within the amplifier 116, the oscillation state (oscillation width and number of oscillations) of the oscillating rollers 101 and 102 can be adjusted (see Japanese Patent Application Laid-Open (kokai) No. 63-264352 and Japanese Utility Model Application Laid-Open (kokai) No. 63-170138).
The conventional oscillation apparatuses as described above have the following problems.
(1) Since the amount and direction of fluid supplied to the hydraulic cylinder 115 are controlled by the flow control valve 113 and the direction control valve 114 to thereby adjust the oscillation width and number of oscillations of the oscillating rollers 101 and 102, the mechanism for controlling the hydraulic cylinder 115 is complicated.
(2) Insufficient responsiveness of the hydraulic cylinder 115 makes it difficult to finely adjust the oscillation width and number of oscillations of the oscillating rollers 101 and 102.
In view of the foregoing, an object of the present invention is to provide an oscillation apparatus for an oscillating roller which can adjust the oscillation state of the oscillating roller with high responsiveness by use of a simple mechanism.
In order to achieve the above object, an oscillation apparatus for an oscillating roller according to the present invention comprises: an oscillation mechanism for reciprocating an oscillating roller which can be rotated in the circumferential direction and can be reciprocated along the axial direction; an oscillation-width adjustment mechanism for adjusting the oscillation width of the oscillating roller; an oscillation-mechanism drive motor for operating the oscillation mechanism; an oscillation-width adjustment motor for operating the oscillation-width adjustment mechanism; oscillation-width control means for controlling operation of the oscillation-width adjustment motor such that the oscillation width of the oscillating roller attains a designated value; and oscillation-number control means for controlling operation of the oscillation-mechanism drive motor, on the basis of the number of revolutions of the plate cylinder, such that the number of oscillations of the oscillating roller per unit number of revolutions of the plate cylinder attains a designated value.
Preferably, the oscillation mechanism comprises a swing member which swings upon operation of the oscillation-mechanism drive motor, a moving member movably supported on the swing member, and an engagement member rotatably supported on the moving member and being in engagement with the oscillating roller; and the oscillation-width adjustment mechanism is configured such that, upon operation of the oscillation-width adjustment motor, the oscillation-width adjustment mechanism moves the moving member to thereby adjust a distance between a swing center of the swing member and a rotation center of the engagement member.
Preferably, the moving member is slidably supported on the swing member.
Preferably, the oscillation mechanism comprises a crank mechanism whose input side is connected to the oscillation-mechanism drive motor; a swingably-supported swing lever whose base end side is connected to the output side of the crank mechanism; a slide lever slidably supported by the swing lever such that the distal end side of the slide lever can move toward and away from a swing center of the swing lever; a first link plate whose one end side is rotatably supported by the distal end side of the slide lever; a swingably-supported swing plate, the other end side of the first link plate being rotatably connected to the base end side of the swing plate; and a cam follower provided at the distal end side of the swing plate and inserted into a groove wheel of the oscillating roller, and in that the oscillation-width adjustment mechanism comprises a worm gear connected to the oscillation-width adjustment motor; a worm wheel in meshing engagement with the worm gear; a transmission shaft coaxially connected to the worm wheel; a second link plate whose one end side is connected to the transmission shaft; and the slide lever whose base end side is rotatably connected to the other end side of the second link plate.
In the oscillation apparatus for an oscillating roller according to the present invention, the oscillation-width control means controls operation of the oscillation-width adjustment motor such that the oscillation width of the oscillating roller attains a designated value; and the oscillation-number control means controls operation of the oscillation-mechanism drive motor, on the basis of the number of revolutions of the plate cylinder, such that the number of oscillations of the oscillating roller per unit number of revolutions of the plate cylinder attains a designated value. Therefore, the control mechanism for the oscillating roller can be simplified. In addition, since the oscillating roller is operated by the above-described motors, the oscillating roller can be operated with high responsiveness, and the oscillation of the oscillating roller can be adjusted finely and easily. Accordingly, the oscillation state of the oscillating roller can be adjusted with high responsiveness by use of a simple mechanism.